typically a MPPT ic such as the LTC3105 is directly connected to the solar cell. To charge a li-Ion battery, a li-ion charger ic is connected to the output. This charger ic e.g. a MAX1551 has a fixed or programmable maximum load current.

I am asking myself, is there any intelligent li-ion charger ic which auto-adjusts the maximum load current based on the maximum current available from the MPPT ic? If there is low light, the MPPC ic will deliver e.g. +5V but with only 10mA. If the battery is almost completely empty, the charger ic will try to load the battery with the maximum current. As the MPPC will act as an step-up, the output will collapse.

Is there any solution available? Setting the maximum load current of the charger to e.g. 1mA is not an option as when not having low light, most of the available energy is vanished.



1 Answer 1


The BQ21040 from Texas Instruments does exactly as described. Have tested it.


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